Complete restoration was not the intention until…………..!
The original plan was to remove the hand lever from the cross shaft to have the chrome plating renewed. This would require removing one cable lever by grinding off two welds and removing two taper pins on the driver side end of the shaft. After the hand lever was removed the wear on the shaft where the hand lever is positioned was quite evident. The two brass bearing sleeves in the end supports were also heavily worn and the decision to rebuild the hand brake cross shaft was made.
Making the two brass bearing sleeves for the end supports and the brass bushing for the hand lever would be straight forward since I have a lathe in my shop. What to do with the shaft needed to be decided.
Options for dealing with wear on the shaft
I felt there were two options:
One option would be to weld up the worn area on the shaft and turn it back to size. This would require that the centre hand brake lever be removed from the shaft by machining off the welds and removing two more taper pins since the worn area is adjacent to this lever. I felt it would be difficult to keep the shaft straight due to the welding on a small diameter tube.
Another option would be to replace the shaft but the challenge here was how to locate the three levers back in their correct positions and relationship to each other. Closer examination revealed that the two cable levers and their taper pins that pull the hand brake cables at each end are in alignment with each other. The centre lever that the hand lever attaches to via the threaded rod with the clevis end would require that it be properly positioned so the cable levers would work correctly.
Preparation for making a new shaft
I made a drilling jig that would hold and locate the shaft when drilling the holes for the three levers. The jig consists of two V blocks and clamps for holding the shaft, an end stop to position the shaft axially and a block with a hole and pin that would lock the position of the shaft when drilling the cable levers on each end. I used the old shaft and before I removed the other two levers I needed to locate the pin hole in the pin block. With the shaft in the V blocks and a steel rod in the taper pin holes at the end of the shaft to help measure that the taper pin holes were vertical, I marked the position of the hole in the pin block and drilled the hole. Now that the jig was made it was time to remove the last two levers and make the new shaft.
Picture 1 shows the drilling jig along with all the parts that make up the assembly)
Picture 2 shows the drilling jig after marking and drilling the hole in the pin block to align with the centre hand brake lever
Making the shaft
I bought a piece of tubing that was 1 1/4” OD and 7/8” ID by 24” long so there was enough length to chuck on in the lathe. My first attempt at turning the shaft on my lathe was unsuccessful as I could not hold the OD size consistent over the whole length of the shaft. On the second attempt I left .010” of stock on the OD and took the shaft to work and asked the fellow that runs the cylindrical OD grinder to finish grind the shaft. He had the same problem of holding size over the length of the shaft. At this point I asked myself why I was trying to hold size the entire length of the shaft. It only needed to be on size on each end plus the area under the centre hand brake levers and stop collar. Again I made a shaft leaving grind stock on the critical areas and undercut the other areas by .005/.010”. This time it was successful.
Using the jig was as simple as putting the old shaft without the centre lever in the jig and positioning the jig on the drill press so that the centre lever hole was aligned with the drill and clamping the jig to the drill press table. Removing the old shaft and putting the new shaft in the jig, the hole was drilled thru both sides of the shaft. The old shaft with the centre lever assembled was put back into the jig with the centre lever temporarily pinned in place and the jig was then positioned so that the holes for one of the cable levers aligned with the drill. Take out the old shaft, assemble the centre lever onto the new shaft, pin it in place and drill thru the shaft again. Repeat the process for the other cable lever on the opposite end. The drilled and tapped hole for the stop collar had no relationship to any other holes but needed to be positioned so that the hand lever and the ratchet plate were a nice fit between the centre lever and the stop collar. I assembled these items so the hole could be marked thru the hole in the stop collar.
While everything was apart I had all the hardware zinc plated and the hand lever chrome plated. The only parts replaced were the ratchet and the pawl.
One modification I made to the bushing in the hand lever was to drill a hole that aligned with the thru hole in the hand lever. This allows the knob to be removed at the top of the hand lever and a few drops of oil can be added so that it can drip down to the shaft and provide a bit of lubrication.
The other parts that needed to be made were the bearing sleeves for the end supports. This was just a matter of turning up the sleeves then mounting them on a mandrel to turn the outside shape. The shape is pretty much three flat lengths connected by a generous radius on each side, not really a true spherical shape. The end supports had to have the rivets drilled out, brass sleeves replaced and then assembled with new rivets although a small nut and bolt could have been used.
The assembly is pretty straight forward with putting on the items on the shaft in the correct order. I made new taper pins for the three levers and welded the levers as originally done. The bottom of the hand lever was previously painted so all the needed to be done was a bit of masking and finish painting the shaft. After the paint was dry, the balance of the items were assembled to the shaft.
This was a fun and challenging project. While not everyone has a lathe at home (I really don’t know how I could manage without one) the shaft could be made by a competent machine shop and the remaining work done at home in a modestly equipped shop.
John Libbert Ohio USA
Ed’s note: The following series of photos show the various steps taken to complete the job.
For readers in the UK and Europe, complete handbrake cross-shaft restoration for Triple-M and TA/B/C cars is undertaken by Digby Elliot. He can be contacted on 07836 754034. His address is ‘Beam Ends’. (at Newton crossroads), Southampton Road, Whiteparish, SALISBURY, Wiltshire SP5 2QL, UK.
Digby has just commissioned some hemispherical bushes and end plates for the TA/TB/TC brake cross-shaft and when I spoke to him during the first week in February he said that he hoped to have these ready for inspection at the Stoneleigh MG Spares Day.
He sells the bushes in two sizes (standard and undersize). The reason for this is that he has found from experience that if the old shaft is being re-used it is usually worn on the ends thereby necessitating the use of undersize bushes.
Picture 3 shows the detail of the pin in the pin block and centre hand brake lever
Picture 4 shows using the old shaft to set the drill jig for drilling the first hole for the centre hand brake lever
Picture 5 shows using the old shaft with the centre hand brake lever pinned in place to set the alignment for drilling the first hole for the cable lever
Picture 6 (right) shows the centre hand brake lever on the new shaft in the drill jig just after drilling the hole for the cable lever
Picture 7 shows the new shaft after all holes drilled and two levers pinned and welded in place
Picture 8 shows the final shape of the bearing sleeve for the end supports
Picture 9 shows the mandrel used to turn the outside shape of the bearing sleeves
Picture 10 shows one view of the finished article
Picture 11 shows another view of the finished article